Forensics Fibers
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What kind of evidence are fibers?
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class
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Do fibers have probative value?
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yes
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Fibers are made of
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twisted filaments
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Natural fibers can be classified as
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vegetable/cellulose, animal/protein, or mineral
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Name 3 synthetic fibers
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rayon,nylon,acetate
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What are synthetic fibers?
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Fibers that are synthesized or created from altered natural sources
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List 6 synthetic fibers
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rayon, nylon, acetate, acrylic, spandex, polyester
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List 2 types of cellulose fibers and their source
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rayon- chemically altered cellulose; soft, lustrous, versatile cellulose acetate- cellulose chemically altered to create an entirely new compound not found in nature (often shiny)
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List two types of protein fibers and their source
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wool- animal fiber coming most often from sheep, but may be goat (mohair), rabbit (angora), camel, alpaca, llama, vicuna silk- insect fiber that is spun by a silk worm to make its cocoon; fiber reflects light and has insulating properties (more unique fibers)
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List two types of mineral fibers and their source
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Asbestos- more unique at a crime scene, a natural fiber that has been used in fire resistant substances rock wool- mass produced, a manufactured mineral fiber (molten rock)
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What is the most common synthetic fiber used in textiles?
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polyester
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What is the most common natural fiber used in textiles?
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cotton
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Can a fiber be individualized to a particular textile fabric? Why or why not?
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No, because fibers are mass produced
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List the 3 types of mass produced weave patterns. Which is most common?
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plain, satin, twill, most common is plain
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Describe three tests for fiber identification
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Burning- Observation of how a fiber burns- ash, hard bead, odor, flame color, color of smoke and the appearance of the residue Thermal decomposition- Gently heating to break down fiber to the basic monomers Chemical tests- Solubility and decomposition if they dissolve in a solvent
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Describe three ways fiber evidence can be collected from a crime scene
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Bag clothing items individually in paper bags. Make sure that different items are not placed on the same surface before being bagged Make tape lifts of exposed skin areas of bodies and any inanimate objects Removed fibers should be folded into a small sheet of paper and stored in a paper bag visible inspection with UV/flashlight
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What is the most incorrect technique for collecting fiber evidence?
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vacuming
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The investigator can only tell the jury
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what similarities were found and give them an idea of how rare these similarities are
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Knitted fabrics are made
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by interlocking the loops into a specific arrangement
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How were fibers relevant to the Wayne William's case?
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Yellow green carpet fibers found in a victim's hair matched those of carpet in his house
